Generator assembly and modular power supply system

ABSTRACT

A generator assembly suitable for being carried on the back of a human comprising an internal combustion engine an alternator and a shaft driven by said engine and driving said alternator wherein when said generator assembly is being carried on the back of human said shaft is substantially parallel to a longitudinal axis of said human. This enhances the maneuverability of the assembly. Preferably the assembly comprises a generator module having an engine and an alternator coupled directly by a common shaft, the generator being attached to a frame of the assembly at only two longitudinally spaced-apart positions.

RELATED APPLICATION

This application is a national phase entry under 35 USC 371 ofInternational Patent Application No PCT/GB2013/000256 filed on 10 Jun.2013, which was published in the English language on 12 Dec. 2013 withInternational Publication Number WO 2013/182836 A1, which claimspriority from GB Patent Application No. 1210294.3 filed on 8 Jun. 2012,the disclosures of which are incorporated in their entirety by referenceherein.

The present invention relates to a generator assembly suitable for beingcarried on the back of a human, particularly to a generator assemblycapable of being carried as a pack on the back of said human. Theinvention also relates to a modular power supply system.

U.S. Pat. No. 5,555,853 discloses a back-pack generator assemblycomprising an engine, an alternator and a shaft driven by said engineand driving said alternator. When the back-pack generator assembly ofU.S. Pat. No. 5,555,853 is being carried on the back of a human saidshaft is substantially orthogonal to a longitudinal axis of said human.

In one aspect the subject invention provides a back-pack generatorassembly suitable for being carried on the back of a human, thegenerator assembly comprising a generator set supported by a pair oflaterally spaced apart shoulder straps, the shoulder straps having alongitudinal axis, the generator set comprising an engine, an alternatorlongitudinally spaced apart from the engine and a shaft assembly fordriving said alternator, wherein one or more shafts of said shaftassembly are substantially parallel to said longitudinal axis.

In preferred embodiments, when the generator assembly is being carriedon the back of a user, the generator is positioned substantially withina periphery of the body of said user so that the user can carry thegenerator assembly without banging the generator assembly on externalstructures, for example a door frame.

Preferably said generator assembly further comprises an elongate framefor being strapped to the back of said human with said straps, saidframe having a longitudinal axis wherein one or more shafts of saidshaft assembly are substantially parallel to said longitudinal axis ofsaid frame. The frame is suitably provided with padded shoulder strapsand belt straps so that the generator assembly can easily andcomfortably be carried on a user's back. The frame also serves tosupport the generator assembly during operation of the generatorassembly when the frame is dismounted from the user.

Preferably said generator set is a module removably attached to saidframe at only two longitudinally spaced-apart positions, said shaftassembly comprising a common shaft coupling said engine and alternatorat an intermediate longitudinal position.

This preferred feature has the advantage that the generator set modulecan easily be dismounted from the frame and exchanged with a differentgenerator set module or a battery pack, for example. The shaft providesthe necessary rigidity of connection between the engine and alternator.

Preferably said common shaft couples said engine to said alternatordirectly without a gearbox. This enhances rigidity and saves weight.

In one embodiment the generator set is secured to the frame by arectangular array of four screwed fasteners, two at each of saidlongitudinally spaced-apart positions.

In one embodiment said module comprises a mounting plate which carriessaid generator set and is removably attached to said frame at said twolongitudinally spaced-apart positions.

Preferably said frame has an array of deployable legs mounted thereonfor supporting said generator set on the ground.

In one embodiment the frame of the generator assembly has four cornerportions each said corner portion having a deployable/retractable legmounted thereon said leg being capable of being deployed for supportingsaid generator assembly on the ground. In other embodiments, differentlyshaped frames may be employed, eg without corner portions or havingthree or more than four corner portions.

In use of such embodiments, a user can easily unload the generatorassembly from his back and quickly position it on the ground bydeploying said legs. The generator assembly is then in a stable positionon the ground and can quickly and easily be started up to provide anelectricity supply.

Preferably said deployable legs are mounted at corner portions of saidframe, are substantially orthogonal to a common plane of said cornerportions and are slidable from a retracted configuration in which thearray of legs surrounds said generator set and projects away from a rearside of the frame on which said generator set is mounted to a deployedconfiguration in which the array of legs projects towards the groundfrom a front side of the frame.

This preferred feature has the advantage that the legs protect thegenerator set while the generator assembly is being carried.

In a preferred embodiment said frame of said generator assembly has afirst end portion of said frame located at one end of a longitudinalaxis of said frame and a second end portion of said frame located at anopposite end of said longitudinal axis said frame further comprising oneor more wheels mounted on said first end portion and a handle mounted onsaid second end portion so that said generator assembly can be pulledalong the ground on said wheels. An advantage of this preferred featureof the generator assembly is that the generator assembly can be easilymoved about on its wheels by a user for positioning said generatorassembly in a desired position.

Further preferred features are defined in the dependent claims.

In another aspect the invention provides a modular back-pack powersupply system comprising an elongate frame having a longitudinal axis, apair of laterally spaced apart shoulder straps, the shoulder strapshaving a longitudinal axis which is substantially parallel with thelongitudinal axis of the elongate frame, and

an elongate generator set module comprising an engine, an alternatorlongitudinally spaced apart from the engine and a shaft assembly fordriving said alternator, wherein said elongate generator set module ismountable on said frame with one or more shafts of said shaft assemblysubstantially parallel to said longitudinal axes to form a back-packgenerator assembly suitable for being carried on the back of a human.

This modular system can be assembled to provide a generator assembly inaccordance with the first aspect of the invention, and, being modular,facilitates replacement or substitution of the generator set module.

Thus in a preferred embodiment, the modular back-pack power supplysystem further comprises a battery module which is removably attachableto said frame in place of said generator set module at mountingpositions which correspond to mounting positions used for the generatorset module.

In a further preferred embodiment the modular back-pack power supplysystem further comprises one or more further generator set moduleshaving different engines.

Preferably said generator set module is removably attachable to saidframe at only two longitudinally spaced-apart positions, said shaftassembly comprising a common shaft coupling said engine and alternatorat an intermediate longitudinal position. The common shaft couplingprovides the necessary rigidity and reduces the required number ofattachment positions on the frame, enabling rapid substitution orreplacement of the generator set module.

In one embodiment the generator set module can be bolted to said frameby a rectangular array of four screwed fasteners, two at each of saidlongitudinally spaced-apart positions.

In one embodiment the frame further comprises one or more substantiallyU-shaped elongated members for supporting a flexible outer cover of saidgenerator assembly over said engine said alternator and said shaftassembly, each end of each of said one or more substantially U-shapedelongated members being located on a portion of said back of said framenear opposite longer sides thereof.

Further preferred features are defined in the dependent claims.

Preferred embodiments of the invention are now described by way ofexample only with reference to FIGS. 1 to 11 of the accompanyingdrawings wherein:

FIG. 1 is a partially cut away view of a first embodiment of thegenerator assembly of the subject invention without gears.

FIG. 1A shows the generator assembly of FIG. 1 in perspective viewshowing an outside view of the engine/alternator etc, dismounted fromthe back of a user.

FIG. 2 is a partially cut away view of a second embodiment of theinvention with said generator assembly having gears.

FIG. 3 is a perspective view of the generator assembly of the inventionshown with its internal components housed within an outer cover.

FIG. 4A is a perspective view of a frame portion of the generatorassembly of the invention with the generator components of the generatorassembly shown dismounted from the frame portion.

FIGS. 4B-4C show the frame portion of FIG. 4A further including portionsof a mounting assembly for mounting the engine and alternator to theframe.

FIG. 4D is similar to FIG. 4C further showing a member for supporting aflexible outer cover of the generator assembly.

FIG. 5 is a front perspective view of a frame assembly of anotherembodiment.

FIG. 6 is a rear perspective view of the frame assembly of FIG. 5.

FIG. 7 is a front perspective view of the frame assembly of FIGS. 5 and6, showing a mounting plate attached to the front of the frame.

FIG. 8 is rear perspective view of the embodiment of FIGS. 5 to 7,showing the generator assembly, shown partially cut away, carried by auser.

FIG. 9 is a side elevation of the generator assembly of FIG. 8, shownsupported on a ground surface with the legs in the deployedconfiguration.

FIG. 10A is a perspective view of the generator assembly of FIG. 8, aspart of a modular power supply system.

FIG. 10B is a perspective view of a similar generator assembly with adifferent engine, forming part of the modular power supply system.

FIG. 10C is a perspective view of a similar generator assembly withanother engine, forming part of the modular power supply system.

FIG. 10D is a perspective view of a battery pack, forming part of themodular power supply system.

FIG. 10E shows a generator assembly of the FIG. 5 embodiment with acover.

FIG. 11 is an exploded perspective view showing the assembly/disassemblyof the generator assembly of FIGS. 8 and 10A.

Throughout the drawings, corresponding parts are indicated by commonreference numerals.

The generator assembly 10 shown in FIGS. 1, 1A and 2 (engine etc. inFIGS. 1 and 2 shown in partially cut away view) has engine 17,alternator 11 and a shaft assembly 100 comprising engine shaft 16 andalternator shaft 12 with said engine shaft 16 coupled to said alternatorshaft 12 so that said engine shaft 16 drives said alternator. Generatorassembly 10 has frame 19 on which is mounted various componentsincluding said engine 17 and said alternator 12 and outer cover portion30 for housing internal components of generator assembly 10 as shown inFIG. 3. Engine 17 and alternator 11 each have lower plate like portions53 and 54 for mounting engine 17 and alternator 11 to frame 19 usingmounting assembly 200 which will be described below with reference toFIGS. 4B-4D. Frame 19 has four corner portions each having a retractableleg 20 a, 20 b, 20 c, 20 d mounted thereon for supporting said generatorassembly on the ground. A user (e.g. human being 150 shown in thedrawings) can quickly unload said generator assembly from his back anddeploy the legs so that the generator assembly can be stably supportedon the ground in which position the generator assembly can be started upfor generating power. FIG. 1A shows the generator assembly of FIG. 1 inperspective view without any engine/alternator portions shown cut away,dismounted from the back of a user. As can be seen from FIG. 1Aalternator 11 has electric sockets 50 a and 50 b mounted on an upperportion thereof. These sockets are capable of being exposed to anexterior of the generator assembly by unzipping a flap of the cover (seeFIG. 3) so that a user can power electrical equipment by plugging intoelectric sockets 50 a and 50 b.

Frame 19 and mounting assembly 200 are best seen in FIG. 4B-4D (whichshows the frame and mounting assembly with other components of thegenerator assembly dismounted therefrom). As shown in FIGS. 3 and 4A-4Dfor example frame 19 comprises a body portion 52 having side portions 28a and 28 b on each side thereof. Side portions 28 a and 28 b have slots60 a-60 f formed therein which cooperate with fasteners formed onexterior portions of cover portion 30 for fastening the cover portion 30of the generator assembly 10 to the frame 19 as will be described inmore detail by reference to FIG. 3 hereof. As can be seen in FIG. 4Aframe 19 has an array of centrally disposed round protrusions 56 a-56 f,each round protrusion 56 a-56 f having a threaded hole 71 a-71 f at acentre thereof for receiving a screw therein so that mounting plate 51(see e.g. FIGS. 1-2 and FIGS. 4B-4C) of mounting assembly 200 can befastened to frame 19. Mounting plate 51 of mounting assembly 200 isshown in FIG. 4B attached to round protrusions 56 a-56 f of frame 19with screws 72 a-72 f. As shown in FIGS. 1, 1A and 2 respective lowerplate like portions 53 and 54 of alternator 11 and engine 17 arefastened to mounting plate 51 of mounting assembly 200. As shown in FIG.4C mounting assembly 200 has upwardly cut off protruding portions 73a-73 d which are cut off portions of bolts used for fastening respectivealternator and engine parts of generator assembly 10 to mounting plate51. In other embodiments (not shown) redundant portions of the mountingplate 51 are cut away to save weight. The cut off portions of the bolts73 a-73 d as shown in FIG. 4C protrude through central portions ofrubber dampers 74 a-74 d which function to dampen the vibrations of theengine and alternator when the generator assembly 10 is in use forgenerating electric power. In other embodiments (not shown) alternativemeans for dampening the vibrations of the engine and/or alternator canbe used for example cable isolators (see www isolator.Com/isolatorseries) either over plate 51 or underneath plate 51 or both and eithercombined with rubber dampeners or not and either under engine only orunder both engine and alternator. Frame 19 is desirably formed from alightweight material so that said generator assembly is sufficientlylight that it can be carried relatively easy by a user. Frame 19 asshown in the Figures is formed from aluminium alloy and is machined outof a solid aluminium alloy block using computerised CNC milling methodswell known to the skilled addressee. Alternatively frame 19 could beformed from magnesium alloy further to reduce weight. Subsequentlyancillary parts of the frame e.g. handles 21 a and 21 b are fixed toframe 19. As can be seen in the Figures (for example FIG. 4A) eachretractable leg 20 a, 20 b, 20 c, 20 d of frame 19 has an locking pullpin 40 a-40 d for locking the leg either in a fully retracted positionor in a chosen deployment position. Locking pull pin 40 a-40 d engageswith holes 81 a-81 c (see FIG. 4A) formed in a circumferential portionof each of retractable legs 20 a, 20 b, 20 c, 20 d for locking each legin a chosen position and each locking pull pin has resilient means forbiasing said pin towards a locked position of said pin. The figures eachshow retractable legs 20 a, 20 b, 20 c, 20 d in fully retracted positionwhereby generator assembly 10 is configured for being carried on theback of a user. Retractable legs 20 a, 20 b, 20 c, 20 d can be deployedinto a deployed position suitable for supporting generator assembly 10stably on the ground. The frame has shoulder straps 24 and belt 25 sothat the generator assembly 10 can be comfortably carried by a user.Desirably said shoulder strap and said belt are padded for additionalcomfort. The frame 19 has a wheel assembly comprising wheels 22 a and 22b mounted for rotation on axle 23. Axle 23 is mounted on a bottom endportion of the frame and the wheel assembly further comprises handle 21b mounted between the wheels 22 a and 22 b. A further handle 21 a ismounted on a top end portion of the frame so that the generator assemblycan be conveniently wheeled about on the ground by a user pulling thegenerator assembly along by its handle 21 a. Alternatively the generatorassembly can be carried from place to place using handles 21 a and 21 b.

Engine 17 has been developed in accordance with the inventor'sspecifications in collaboration with Ricardo Plc which is amultinational company operating in various countries including the UK.Ricardo Plc can be contacted through its affiliate Ricardo UK, ShorehamTechnical Centre, Shoreham-by-Sea, West Sussex BN43 5FG. Engine 17 is amodified version of Ricardo's 3 hp UAV engine, specifications of whichwere published in Ricardo's IRAD update in 2010.

Engine 17 puts out 6 HP and is a multi fuel spark ignited twin piston“boxer” type engine, utilising a mechanically compressed directinjection (MCDi) system which combine fuel and air using a compressor.The fuel and air mixture is injected into the combustion chamber of eachcylinder through a delivery timed valve in an atomised/molecularizedstate, allowing even heavy fuels to ignite at lower temperatures. Thisatomisation/molecularization technology can operate on a variety offuels for example diesel, bio diesel, Ethanol, Kerosene, JP5, JP8, Jet Aand gasoline.

Engine 17 drives engine shaft 16 which in turn drives alternator shaft12 of alternator 11. Engine shaft 16 is coupled to alternator shaft 12by a coupling means as discussed in more detail below. Alternator 12 isan asynchronous alternator which is commercially available fromMetallwarenfabrik Gemmingen Gmbh, of Postfach 9-75046 Gemmingen

TEL: +49(0)7267 8060 FAX: +49(0)7267 806 100. See alsowww.metalwarenfabrik.com. Alternator 12 is a Metallwarenfabrik GemmingenGmbh type identified as ‘2801 GEKO/EISEMANN Modell 2008’. In otherembodiments other asynchronous generators can be used. In alternativeembodiments synchronous alternators can be used. In other embodiments ofthe generator assembly 10 different engines can be used, provided theyhave sufficient power output to drive a chosen alternator.

As shown in FIG. 1 engine shaft 16 is coupled to alternator shaft 12 bya coupling means which does not include gears. Engine shaft 16 andalternator shaft 12 are each disposed along a common axis 18 as shown.

In the embodiment of the inventive generator assembly as shown in FIG. 2engine shaft 16 and alternator shaft 12 are coupled by a coupling meanswhich includes gear box 15. Gear box 15 has gear wheels 14A and 14Bwhich are capable of being placed in gear with each other or out of gearwith each other by means well known to the skilled addressee. In theembodiment shown in FIG. 2 engine shaft 16 and alternator shaft 12 areeach disposed along separate axes, said separate axes beingsubstantially parallel with each other. Each of the engine shaft 16 andthe alternator shaft 12 can rotate either in a clockwise direction or ananticlockwise direction as shown respectively by arrows “X” and “Y” inFIGS. 1 and 2. A shaft assembly 100 comprising respective shafts 16 and12 is substantially parallel to a longitudinal axis of the human being150 carrying the alternator assembly of the subject invention as shownin the drawings. As a result of the shaft assembly 100 being disposed inthis way when the generator assembly is being carried on the back of thehuman 150 said generator assembly is positioned substantially within aperiphery of the body of the human so that the human can carry thegenerator assembly without banging the generator assembly on externalstructures for example a door frame. The generator assembly 10 as shownis capable of providing over 2,000 watts of electrical power preferably2,000 to 2,500 watts of electrical power. The generator assembly 10 canbe used to drive power tools up to the rated output, putting out forexample either on 230V and 50 Hz frequency or on 120V and 60 hzfrequency. Additionally it has a DC outlet for either 12V or 24V.

FIG. 3 shows the generator assembly of the subject invention with itsinner components which are shown and described herein housed withinouter cover portion 30. Cover portion 30 is preferably formed fromlayers of textile stitched together to form a flexible cover which isstretched over support members 301 (see FIG. 4D) of frame 19 and thenfastened to said generator assembly thereby covering the internal (e.g.engine) components of the generator assembly as can be seen in FIGS. 3and 4D. Cover portion 30 has fasteners 86 a-86 c affixed thereto forreleasably fastening the cover portion 30 of the generator assembly toframe 19. Each fastener 86 a-86 c has an upper portion securely fixed(e.g. sowed) to cover portion 30 and a lower portion which engages witheach corresponding slots 60 a-60 f formed in side portions 28 a and 28 bof frame 19 for releasably fastening the cover portion 30 of thegenerator assembly to frame 19. Cover portion 30 can easily be removedfrom generator assembly 10 by releasing fasteners fasteners 86 a-86 cfrom corresponding slots 60 a-60 f of frame 19 for example for servicingengine 17 or alternator 11. Cover portion 30 preferably is a compositecover portion comprising a lower fabric layer positioned closest to thesaid internal components which is porous to sound waves coming from theengine etc, a middle sound absorbing layer, and an outer fabric layerwhich is weather resistant preferably waterproof and relatively notporous to sound. Sound waves coming from the engine etc are thenpreferably absorbed as follows. The sound passing through the said lowerfabric layer positioned closest to the said internal components arepartially absorbed by the middle sound absorbing layer and then bounceoff the said outer layer (relatively not porous to sound) back into themiddle layer where more sound absorbing occurs. The said lower fabriclayer positioned closest to the said internal components is for exampleformed from a Cordura and Fibreglass fabric (also having fire resistantproperties). Cordura is an Invista brand of Dupont. The said middlesound absorbing layer is for example formed from Basotect or Glasswool.Basotect is a brand name of a family of products for sound insulationmade from foamed melamine resin. The said outer fabric layer which ispreferably waterproof and relatively not porous to sound is for examplea Cordura and silicon coated fibreglass fabric or nylon. In alternativeembodiments (not shown) the outer cover portion is a rigid compositematerial formed of two or more layers, for example the outer layer beinga rigid carbon fibre/composite cover and the inner layer being aninsulation material e.g. Basotect or fibreglass wool. Optionally anadditional ballistic resistant fabric inner layer could be added to forma ballistic resistant cover portion 30. Cover portion 30 has openingsfor components such as fuel tank lid 36 engine start handle 90 andelectric sockets 50 a and 50 b (see for example FIGS. 1A and 3) andoptionally for other sockets and/or control panels of theengine/generator (not shown) which are preferably exposed to theexterior either for manipulation or viewing by a user of the generatorassembly 10. As can be seen from FIG. 3 generator assembly 10 has enginestart handle 90 exposed to the outside through opening ‘D’ which openingcan be opened/closed by unzipping/zipping up the zipper shown by dottedlines. Generator assembly 10 also has electric sockets and optionally acontrol panel which are shown in FIG. 3 covered by zipped up opening Cof cover portion 30 and which can be exposed to the exterior byunzipping the zip shown by dotted lines surrounding area C. Area B shownsurrounded by dotted lines in FIG. 3 shows the position of a fuel tankfor engine 17. Other materials can be used to make cover portion 30 aswould be well known to the skilled addressee. The fuel tank can be madefrom conventional rigid materials for making fuel tanks for examplemetals as is well known to the skilled addressee. Alternatively the fueltank is made from a flexible bladder like material for example a triplelayer polyethylene film. Optionally such a bladder type fuel tank cancomprise a one way breather valve in addition to the usual fuel outletassembly which avoids the formation of a vacuum in the bladder and inaddition enabling the operator to inflate portions of the interior ofthe bladder that are empty of fuel with air to give the bladder shapeand slight pressure to push the remaining fuel to an outlet valve of thefuel outlet assembly. An advantage of having a bladder type fuel tankarises when the generator assembly is being used by a group of emergencypersonnel for example during a rescue mission. Spare fuel bladders (e.g.3 liter bladders) filled with extra fuel for powering the generatorassembly can then conveniently be carried by several members of thegroup of emergency personnel thereby providing extended operational timefor the generator. Roughly speaking 3 liters of fuel will give up to 3hours of engine time. Alternatively the flexibility of a bladder typefuel container enables the attachment of the bladder to a portion of thecover portion 30 of the generator assembly or the insertion of thebladder into a portion of the cover portion 30 of the generatorassembly. The generator assembly described herein is suitable foremergency use and can be carried by for example search/recovery/policepersonnel during rescue missions who might wish to power emergencyequipment, lighting equipment, night sight equipment or other electricalequipment from it. The generator assembly described herein is alsosuitable for other civilian or military use.

FIGS. 5 and 6 show a frame assembly somewhat similar to that of FIGS. 4Ato 4D. However, in accordance with a preferred feature of the invention,attachment points, in the form of threaded bosses 173 (FIG. 5) areprovided at two longitudinal positions near the top end and bottom endof the frame 19. Bosses 173 are disposed in an elongate rectangulararray which is aligned with the longitudinal axis 190 of the frame 19and the longitudinal axis 180 defined by the mid-plane of shoulderstraps 24 (see FIG. 6).

As best seen in FIG. 6, the frame assembly is also provided with rigidforwardly extending stabiliser arms 125 on either side of its lower end.These fit round the waist of the user and stabilise the load. The lowerends of shoulder straps 24 can either be secured (by means not shown) tothe stabiliser arms 125 or can pass through slots (not shown) in thesestabiliser arms to attachment points on the lower end of the frame 19.

FIG. 7 shows a mounting plate 51 aligned with the frame assembly ofFIGS. 5 and 6. Mounting plate 51 is provided with an elongaterectangular array of holes 174 a, 174 b which register with threadedbosses 173.

As shown schematically in FIG. 8, a generator set 10, similar to that ofFIGS. 1 and 1A and employing a Ricardo multi-fuel engine 17, is mountedon mounting plate 51, by means of bolts (not shown) through holes inmounting portions (not shown) of the generator set. These bolts passthrough holes 174 a, 174 b and are screwed into threaded bosses 173.

FIG. 9 shows the generator assembly of FIG. 8 dismounted from the user150 and supported horizontally on a ground surface. To this end,cylindrical legs 20 a-20 d are deployed by withdrawing their associatedlocking pins 40 a-40 d, sliding them through their mounting apertures sothat they project forwardly (ie downwardly in FIG. 9) through frame 19,and then securing them in this configuration by re-inserting the lockingpins. It will be seen that the longitudinal frame axis 190 is roughlyhorizontal and is parallel to the common shaft assembly 16, 12 of theengine 17 and alternator 11.

The legs 20 a-20 d can be retracted to allow the left hand end ofgenerator assembly to be lifted at handle 21 a and moved on its wheels22 b to another location if required. Alternatively, minor adjustmentsto the position of the generator assembly can be made by lifting it ator dragging it using handle 21 b and/or handle 21 a.

FIG. 10A shows the generator assembly of FIG. 8 used as part of amodular power supply system using different generator sets and also abattery pack as described below. FIG. 10A also shows the compressor andatomiser assembly 126 of multi-fuel engine 17.

FIG. 10B shows a further generator assembly using a different generatorset 10. This uses the same alternator as that of FIG. 10A but engine 17′is a commercially available Honda GX-160 petrol engine.

FIG. 10C shows a further generator assembly using a different generatorset 10. This uses the same alternator as that of FIG. 10A but engine 17″is a commercially available Yanmar L series (eg a Yanmar L48) dieselengine.

FIG. 10D shows a lithium ion rechargeable battery pack 130 mounted on amounting plate 51 of a frame 19 instead of a generator set. It isenvisaged that the resulting power supply module could be used with oneor more of the modules of FIGS. 10A to 10C as a temporary power sourceeg at the site of a natural disaster or in other emergency situations,providing both AC and DC power supply.

FIG. 10E shows the provision of a protective cover 30 over one of theabove-described power supply modules. This may have eg properties ofsound absorbance for silencing said internal components of a generatorassembly and/or ballistic resistant properties and/or waterproofingproperties and/or fire proofing properties.

FIG. 11 shows the disassembly or assembly of the power supply module ofFIG. 10A. This involves the unscrewing or screwing of only four boltsthrough holes 174 a in mounting plate 51. Thus the power supply modules,using a common frame 19 and mounting plate 51, can easily be modified,serviced and re-assembled.

Modifications may be made to all the described embodiments. For examplethe harness may be modified in accordance with US 2012/0043361A whichdiscloses a sliding plate at the top of the frame and an unfolding hingeassembly at the bottom of the frame. These allow a load to be movedforward towards a user's shoulders when the user is crawling or lyingdown, which improves ergonomics in some circumstances and enables aheavier load to be carried.

Furthermore a dynamo (generating DC) could be utilised instead of analternator as in the described embodiments. In general any suitablegenerator (ie DC or AC) may be used.

Typically, generator assemblies in accordance with the invention arecapable of providing at least 2000 watts of electrical power and have aweight of less than 40 kilograms.

In the described embodiments the frame 51 is a plate like framesubstantially rectangular in shape and having a front for being placedadjacent the back of the user 150 and a back having mounted thereon theengine 17, the alternator 11 and the shaft assembly 16, 12. Howevernon-rectangular frames may be used in other embodiments.

In the described embodiments each of the longer sides of frame 51 has anarray of slots formed therein for engaging with corresponding fastenersaffixed to an outside of outer cover portion 30 for removably fixing theouter cover portion to the frame 19. However the outer cover portion maybe fixed to the frame 19 in other ways.

The invention claimed is:
 1. A back-pack generator assembly suitable forbeing carried on the back of a human, the generator assembly comprisinga) a generator set (10) supported by a pair of laterally spaced apartshoulder straps (24), the shoulder straps having a longitudinal axis(180), the generator set comprising an engine (17), an alternator ordynamo (11) longitudinally spaced apart from the engine and a shaftassembly for driving said alternator or dynamo, wherein one or moreshafts (16, 12) of said shaft assembly are substantially parallel tosaid longitudinal axis and b) an elongate frame (19) configured forbeing strapped to the back of said human with said straps, said framehaving a longitudinal axis wherein one or more of the shafts of saidshaft assembly are substantially parallel to said longitudinal axis ofsaid frame wherein said generator set is a module removably attached tosaid frame at only two longitudinally spaced apart positions (174 a, 174b) said shaft assembly comprising a common shaft (16, 12) coupling saidengine and alternator or dynamo at an intermediate longitudinalposition.
 2. A back-pack generator assembly according to claim 1,wherein said generator set (10) is secured to said frame (19) by arectangular array of four screwed fasteners (174 a, 174 b), two at eachof said longitudinally spaced-apart positions (174 a, 174 b).
 3. Aback-pack generator assembly according to claim 2, wherein said modulecomprises a mounting plate (51) which carries said generator set (10)and is removably attached to said frame (19) at said two longitudinallyspaced-apart positions.
 4. A back-pack generator assembly according toclaim 2 wherein said common shaft (16, 12) couples said engine (17) tosaid alternator (11) directly without a gearbox.
 5. A back-packgenerator assembly according to claim 1, wherein said frame (19) has anarray of deployable legs (20 a to 20 d) mounted thereon for supportingsaid generator set (10) on the ground.
 6. A back-pack generator assemblyaccording to claim 5, wherein said deployable legs (20 a to 20 d) aremounted at corner portions of said frame (19), are substantiallyorthogonal to a common plane of said corner portions and are slidablefrom a retracted configuration in which the array of legs surrounds saidgenerator set (10) and projects away from a rear side of the frame onwhich said generator set (10) is mounted to a deployed configuration inwhich the array of legs projects towards the ground from a front side ofthe frame.
 7. A back-pack generator assembly according to claim 1,wherein said elongate frame (19) has one or more wheels (22 a, 22 b) atone end thereof and a handle (21 a) at another end thereof to enable thegenerator assembly to be pulled along the ground on said one or morewheels.
 8. A back-pack generator assembly as claimed in claim 1, saidgenerator assembly further comprising an outer cover portion (30) forhousing internal components of said generator assembly.
 9. A back-packgenerator assembly as claimed in claim 8, wherein said frame (19) has aperipheral array of slots (60 a-60 f) formed therein for engaging withcorresponding fasteners (86 a-86 c) affixed to an outside of said outercover portion (30) for removably fixing said outer cover portion to saidframe.
 10. A back-pack generator assembly as claimed in claim 8 whereinsaid outer cover portion (30) has properties of sound absorbance forsilencing said internal components of said generator assembly and/orballistic resistant properties and/or waterproofing properties and/orfire proofing properties.
 11. A back-pack generator assembly as claimedin claim 8, said outer cover portion (30) being a rigid or flexiblecomposite material formed of two or more layers.
 12. A back-packgenerator assembly as claimed in claim 1, wherein said engine (17) issuitable for being fuelled by middle distillate fuel, said enginefurther comprising an atomizing assembly (126) for atomizing said middledistillate fuel such that said middle distillate fuel can be ignited bya spark.
 13. A back-pack generator assembly as claimed in claim 12,wherein said engine (17) further comprises a compressor (126) forfeeding said middle distillate fuel through said atomizing assemblyunder pressure.
 14. A back-pack generator assembly as claimed in claim1, wherein said engine (17) is a boxer type engine.
 15. A back-packgenerator assembly as claimed in claim 1, wherein said alternator (11)is an asynchronous alternator.
 16. A modular back-pack power supplysystem comprising an elongate frame (19) having a longitudinal axis, apair of laterally spaced apart shoulder straps (24), the shoulder strapshaving a longitudinal axis (180) which is substantially parallel withthe longitudinal axis of the elongate frame, and an elongate generatorset module (10) comprising an engine (17), an alternator or dynamo (11)longitudinally spaced apart from the engine and a shaft assembly fordriving said alternator or dynamo, wherein said elongate generator setmodule is mountable on said frame with one or more shafts (16, 12) ofsaid shaft assembly substantially parallel to said longitudinal axes toform a back-pack generator assembly suitable for being carried on theback of a human; wherein said generator module is removably attachableto said frame at only two longitudinally spaced-apart positions (174 a,174 b) said shaft assembly comprising a common shaft (16, 12) couplingsaid engine and alternator at an intermediate longitudinal position. 17.A modular back-pack power supply system according to claim 16, whereinsaid generator set module (10) is removably attachable to said frame(19) at only two longitudinally spaced-apart positions (174 a, 174 b),said shaft assembly comprising a common shaft (16, 12) coupling saidengine (17) and alternator (11) at an intermediate longitudinalposition.
 18. A modular back-pack power supply system according to claim17, wherein said generator set module (10) can be bolted to said frame(19) by a rectangular array of four screwed fasteners (174 a, 174 b),two at each of said longitudinally spaced-apart positions (174 a, 174b).
 19. A modular back-pack power supply system according to claim 16,further comprising a battery module (130) which is removably attachableto said frame (19) in place of said generator set module (10) atmounting positions (174 a, 174 b) which correspond to mounting positions(174 a, 174 b) used for the generator set module.
 20. A modularback-pack power supply system according to claim 16, further comprisingone or more further generator set modules (10) having different engines(17).
 21. A modular back-pack power supply system according to claim 16wherein said generator set module comprises a mounting plate (51) whichcarries said generator set (10) and is removably attachable to saidframe (19).
 22. A modular back-pack power supply system according toclaim 16, wherein said generator set module comprises a generator set(10) wherein said shaft assembly comprise a common shaft which couplessaid engine to said alternator directly without a gearbox.
 23. A modularback-pack power supply system according to claim 16, wherein saidalternator is an asynchronous alternator.
 24. A modular back-pack powersupply system according to claim 16, wherein said generator set modulecomprises a frame (19) having an array of deployable legs (20 a to 20 d)mounted thereon for supporting said generator set (10) on the ground.25. A modular back-pack power supply system according to claim 16,wherein said elongate frame (19) for being strapped to the back of saidhuman with said straps (24) wherein said elongate frame (19) has one ormore wheels (22 a, 22 b) at one end thereof and a handle (21 a) atanother end thereof to enable the generator assembly to be pulled alongthe ground on said one or more wheels.